In-situ fabrication of PEDOT/Fe3O4 in closed-cells of epoxy foams for intelligent electromagnetic interference shielding

Microcellular polymer composites with an excellent conductivity are greatly desired for electromagnetic interference (EMI) shielding applications, but it still remains a great challenge to fabricate conductive composite foams with intelligent EMI shielding performance at minimal amounts of functional filler. Herein, a novel and facile technology is developed for in-situ creating poly(3,4-ethylenedioxythiophene)/ferroferric oxide (PEDOT/Fe 3 O 4 ) in the closed-cells of bulk epoxy foams without sacrificing the lightweight and mechanical properties. Via vapor phase polymerization of EDOT monomer using FeCl 3 as oxidant and followed by alkali treatment, the in-situ generated PEDOT/Fe 3 O 4 composites densely pack at the inner walls of closed-cells to form the highly conductive islands. These islands are linked by the nanofiller/PEDOT conductive chains in cell walls, thus constructing the unique “island-chain” segregated conductive nanostructure. This architecture endows the resultant composite foams with good conductivity, outstanding EMI shielding effectiveness, highly effective absorbance (A eff ), epsilon-negative (ε′ < 0) response and considerable compressive strength, showcasing obvious advantages as compared to conventional design in open-cells. Moreover, these functional composite foams display a repeatably pH-sensitive EMI shielding performance with a significant difference of 14 dB, providing a potential approach for intelligent EMI shielding.